Zoonotic Tick Borne Pathogens in Ticks at Human-Wildlife-Livestock interfaces in Kwale County, Kenya

Abstract

BackgroundTicks are vectors that can harbor pathogens like viruses, protozoa and bacteria that can cause zoonotic diseases in human. Human gets infected through tick bites where the pathogens are passed to the human blood. One tick bite can lead to transmission of more than one disease. Ticks are obligate hematophagous, infest most vertebrates globally. Lack of surveillance information about the tick-borne pathogens and diseases has made it impossible to assess its impact to the community. Materials and MethodsWe morphologically identified ticks collected from two game reserves in Kenya, locations near the Shimba Hills National Reserve (SHNR) and Tsavo National Reserve (TNR). We identified tick-borne pathogens by HRM analysis and sequencing of specific RT-PCR products of Anaplasma, Ehrlichia, and Rickettsia. ResultsA total of 317 (281 adult ticks and 36 nymphs) was collected at near Tsavo National Reserve in Taita Taveta County, which includes seven species. Amblyomma was the most sampled genus with Amblyomma gemma being the most sampled species (n=135, 42.6%). Other Amblyomma species sampled was Amblyomma Variegatum (n= 40, 12.62%). Greatest species diversity was identified in Rhipicephalus genus with four species identified that includes; Rhipicephalus appendiculatus (n=44, 13.9%), Rhipicephalus Averts (n=1, 0.31%), Rhipicephalus Decoloratus (n=5, 1.6%), Rhipicephalus Pulchellus (n= 91, 28.7%). A single species of Hyalomma sp. was sampled. From near Shimba Hill game reserve (SHNR), a total of 240 adults ticks were sampled that comprises of eight species. Amblyomma was the most sampled genus and again Amblyomma gemma being the most sampled species (n=156, 65 %). Other Amblyomma species sampled includes; Amblyomma Lepidum (n= 5, 2.1 %), Amblyomma Variegatum (n= 15, 6.3 %). Greatest species diversity was also identified in Rhipicephalus genus with four species identified that includes; Rhipicephalus appendiculatus (n=18, 7.5 %), Rhipicephalus Averts (n=6, 2.5 %), Rhipicephalus Decoloratus (n=4, 1.7 %), Rhipicephalus Pulchellus (n= 34, 14.2 %). The least sampled species was a single species of Hyalomma Scupense (n=2, 0.83 %). At near Tsavo National Reserve (TNR) in Taita Taveta County, a total of three pools of Rhipicephaline appendiculatus were positive for Theileria parva, two pools of Rhipicephaline evertsi for Anaplasma platys and one pool of Amblyomma variegatum nymphs for Rickettsia africae. From near Shimba Hill game reserve (SHNR), Kwale County, Rickettsia africae pathogen was detected in two pools of Am. variegatum and one pool of Am. Gemma. Rickettsia sp. and Anaplasma sp. were detected in Am. Gemma and Rh. evertsi respective. R. aeschlimannii was detected in a pool of Am. Gemma. These findings highlight the risk of transmission of zoonotic R. africae and unclassified Rickettsia spp. to humans causing African tick-bite fever and other spotted-fever group rickettsioses.